GB1185771A - Improvements in or relating to Winch Arrangements for use in Transferring Articles between Relatively Moving Stations - Google Patents

Abstract

1,185,771. Winches. GENERAL ELECTRIC & ENGLISH ELECTRIC COMPANIES Ltd. 24 Jan., 1969 [25 Jan., 1968], No. 3995/68. Heading B8B. An arrangement for damping tension oscillations in a support cable 7 for transferring a load carrying trolley 9 between two relatively oscillating ships 1, 2 comprises a tensioned cable 16 connected to both ships for monitoring the variable distance therebetween whereby variable control signals related to the distance are generated, the signals being modified in response to tension variations in the support cable 7, and the effective lengths of the cable 7 being controlled in response to these modified signals. The support cable 7 looped between the ships includes a portion 12 on which the trolley 9 runs and a portion 11 fixed to the trolley to move it, the ends of the cable extending from winches 4, 5 on the ship 1. The cable 16 is wound on a constant tension hydraulic winch 6 on the ship 1 and a tachometer generator 19 associated therewith produces a signal related to the rate of change of distance between the ships, this signal being used to control the pump delivery for the hydraulic motors of the support cable winches 4, 5. This signal is however modified by an error signal generated by comparing a nominal tension signal with signals relating to the prevailing tensions in sensors 17, 18 on the support cable portions 11, 12. The velocity of transference of the trolley 9 is controlled relative to the ship 1 within a "clearance distance", as the trolley departs therefrom until a "transition distance" is reached when the velocity gradually becomes relative to the ship 2. Signals from a revolution counter 21 on the winch 4 related to the length of cable payed out are compared with constants representing the "clearance distance" and "transition distance" whereupon relative motions of the ships are accommodated by control of the winch 5 within the "clearance distance" and by both winches 4 and 5 equally in the "transition distance". Pivoted catcher arms 31, 32 on the ships lower the trolley to the ship's deck via rams 35 once the trolley has been received in the appropriate arm. In another embodiment the trolley is lowered by feeding a dummy signal to the winch control system whereby the cable 7 becomes slack to lower the trolley. In a further embodiment, Fig. 5 (not shown), the load engaging portion of the trolley is mounted so that it may be lowered from the trolley on to the deck by slackening the lower position of the support cable.